This invention relates to sample conveyors for measuring systems, more particularly to sample conveyors suitable for use in systems for making repeatitive measurements on a large number of consecutive samples; it also relates to individual components of such conveyors and in particular to cassettes for receiving a plurality of samples and enabling the same to be handled en bloc.
An important but not exclusive use of the invention is in systems for counting the radio-activity of samples in test tubes or vials. Most present art liquid scintillation counters use automatic sample changers comprising a sample conveying chain conveyor. All the samples loaded in the conveyor are brought consecutively to an elevator which moves down the sample to a counting station where its activity is determined and then returns the sample to the same link of the conveyor. Automatic sample changers of this kind are simple and reliable but their capacity is limited to the number of links in the conveyor, they are bulky and the samples must be placed in the chain links one at a time.
Another prior art automatic sample changer comprises trays or racks into which samples can be placed outside the apparatus, the trays or racks then being placed in the changer. A mechanism which is much more complex and slower than the conventional elevator system is then needed to transfer the samples to the counting station.